Telescopic tube catheters of expandable wing type are well known, exemplary of which is that disclosed in U.S. Pat. No. 3,108,595 to Overment. In such type, the distal ends of the tubes are secured together, longitudinal angularly spaced slits are provided in the outer tube adjacent its distal end so that when the tubes are slid relatively, the wings formed between the slits are expanded to prevent unauthorized removal from a body passage. Suitable means are also provided to lock the wings in expanded position. Since the tubes are normally provided with some clearance therebetween to render them readily slideable, fluids may leak through the clearance to the outside of the catheter which is objectionable for obvious reasons.